1. Field of the Invention
The present invention relates to a support device for transferring moving loads from one concrete structure to an adjacent concrete structure. The device being particularly relevant for maintaining the spacial relationship between adjoining concrete paving slabs that are spaced apart by a paving joint.
2. Description of the Prior Art
The use of joint dowels to tie adjoining paving slabs is well known in the art. These dowels are positioned within the concrete formwork, when formwork is used, prior to pouring the concrete so that the dowels extend through the paving joints and are encased in both of the adjoining paving slabs. When slip form paving equipment is being used, the dowels are positioned on the subgrade spaced inwardly from the future longitudinal edge of the slab. The dowels prevent vertical movement between adjoining slabs at a paving joint so that a load moving from one of the slabs is smoothly transferred to the adjacent slab. There are many different types of concrete paving joints that use load transfer devices. The most prevalent are transverse contraction joints, formed to compensate for the shrinkage that occurs in freshly poured concrete. Other paving joints include transverse and longitudinal expansion joints, transverse and longitudinal construction joints and longitudinal contraction joints. During construction the dowels are positioned in the forms at a predetermined distance from the bottom of the slab and are spaced along the paving joint.
Various devices exist that support and hold the dowels in the proper position during the pour of the concrete slab. For example U.S. Pat. No. 2,768,562, issued to William S. Godwin discloses a rather complex arrangement of supports that requires a large amount of labor for field assembly, including attachment of the supports to the sides of the forms. The dowels are maintained longitudinally by a pair of baskets that are formed by welding and are fitted to a support frame.
In U.S. Pat. No. 3,397,626 issued to J. B. Kornick et al., the dowels extend between loops formed in opposing frames. To hold the dowels firmly in place they are welded to one of the loops. This welding operation must be accomplished at the plant where the wire frames are constructed or must be welded in the field, increasing the costs.
Since it is highly desirable that the dowels be held firmly in place during the pouring of the concrete, many support systems require that the dowels be tack welded to a support frame before it is delivered to the construction site. Such requirements increase the assembly and transportation cost, as the frames with the tack welded dowels attached are bulky and awkward to ship. This method of assembly has reduced the labor in the field but has increased the fabrication and shipping costs. Therefore, what is needed is a device where the dowels may be easily locked to the support frames in the field with little labor required.
It has been pointed out that the prior art is either so complex that it is expensive to make; or requires welding at the plant or in the field increasing the cost for labor or transportation. Therefore, it remains clear that there is a need for a device to support load transfer dowels that is simple to manufacture, easily stacked for transportation and easily installed in the field, providing a tight connection without welding.